With rapid development of speech and audio compression technologies, various speech and audio coding algorithms emerge successively. During processing of a speech and audio coding algorithm, a temporal envelope needs to be calculated. An existing process of calculating and quantizing a temporal envelope is as follows. Dividing a preprocessed original high-band signal and a predicted high-band signal separately into M subframes according to a preset quantity M of temporal envelopes for calculation, where M is a positive integer, performing windowing on a subframe, and then calculating a ratio of energy or an amplitude of the preprocessed original high-band signal to that of the predicted high-band signal in each subframe. The preset quantity M of the temporal envelopes for calculation is determined according to a lookahead buffer length. A lookahead buffer means that in a current frame, for a need of calculating some parameters, some last samples of an input signal are buffered and are not used, but are used when the parameters are calculated in a next frame, where samples buffered in a previous frame are used for the current frame. These buffered samples are a lookahead buffer, and a quantity of the buffered samples is a lookahead buffer length.
A problem existing in the foregoing process of processing a temporal envelope is that when a temporal envelope is solved, a symmetric window function is used, and in addition, to ensure inter-subframe and inter-frame aliasing, multiple temporal envelopes are calculated according to the lookahead buffer length. However, during calculation of a temporal envelope, if time-domain resolution of a signal is excessively high, discontinuous intra-frame energy is caused, thereby causing an extremely poor auditory experience.